Electric and magnetic fields effects on the excitonic properties of elliptic core-multishell quantum wires

The effect of eccentricity distortions of core-multishell quantum wires on their electron, hole and exciton states is theoretically investigated. Within the effective mass approximation, the Schrodinger equation is numerically solved for electrons and holes in systems with single and double radial heterostructures, and the exciton binding energy is calculated by means of a variational approach. We show that the energy spectrum of a core-multishell heterostructure with eccentricity distortions, as well as its magnetic field dependence, are very sensitive to the direction of an externally applied electric field, an effect that can be used to identify the eccentricity of the system. For a double heterostructure, the eccentricities of the inner and outer shells play an important role on the excitonic binding energy, specially in the presence of external magnetic fields, and lead to drastic modifications in the oscillator strength.Comment: 17 pages, 10 figure

Genetic diversity and population structure of llamas (Lama glama) from the Camelid Germplasm Bank—Quimsachata

Universidad Nacional Agraria La Molina. Escuela de Posgrado. Maestría en Producción AnimalLlamas (Lama glama) are invaluable resources of Peru. Despite their importance, their population is decreasing. The Camelid Germplasm Bank—Quimsachata was created as a guardian of this South American camelid (SAC) species and established a bank of llamas from their two types, Ch’aku and Q’ara. However, these populations need to present high genetic diversity to be considered suitable conservation stocks. Thus, in the present study, 13 microsatellites specific for the SAC were used to assess the current genetic variability and differentiation of the llama population from the Bank. The global population showed high genetic diversity with a total of 157 different alleles, with an average of 12.08 alleles per microsatellite, an expected and observed heterozygosity of 0.758 and 0.707, respectively, and an average polymorphic information content (PIC) of 0.723. Although considered as two different breeds and managed separately, the genetic differentiation between Ch’aku and Q’ara was low (FST = 0.01). Accordingly, the gene flow value was high (Nm = 30.5). Overall, our results indicate the existence of high genetic variation among individuals, and thus, this llama population could be considered a suitable genetic stock for their conservation and for sustainability programs. Additionally, the 13 microsatellites can be used to study other Peruvian llama populations and monitor the genetic variability of llamas from the Camelid Germplasm Bank—Quimsachata

Os aningais: um tipo de vegetação "quase extinta nas cidades amazônicas".

Os aningais são compostos principalmente pela planta conhecida regionalmente como Aninga (Montrichardia arborescens Schott), uma Araceae que pode atingir 3 a 4 m de altura ocorrendo em densa sinúsia quase monoespecífica caracterizando a paisagem aningal. O objetivo desse trabalho é alertar para a destruição dos remanescentes de aningais nessas cidades e identificar as espécies que ocorre nessa região

Improving light harvesting in polymer photodetector devices through nanoindented metal mask films

To enhance light harvesting in organic photovoltaic devices, we propose the incorporation of a metal (aluminum) mask film in the system’s usual layout. We fabricate devices in a sandwich geometry, where the mask (nanoindented with a periodic array of holes of sizes d and spacing s) is added between the transparent electrode and the active layer formed by a blend of the semiconducting polymer P3HT and substituted fullerene. Its function is to promote trapping of the incident light into the device’s cavity (the region corresponding to the active layer). For d, we set a value that allows light diffraction through the holes in the relevant absorption range of the polymer. To optimize the mask structure, we consider a very simple model to determine the s leading to trapped fields that are relatively intense and homogeneous within the device. From measurements of the action spectra, we show that, indeed, such architecture can considerably improve the resulting photocurrent efficiencies—one order of magnitude in the best situation studied.

A Review on Geotrichum Lipases: Production, Purification, Immobilization and Applications

Lipases are enzymes produced from innumerous microorganisms, plants and animal cells. They catalyze reactions of different lipid sources. The Geotrichum fungi are good producers of lipases with high hydrolytic activity and specificity for unsaturated fatty acids. A great number of studies have reported the importance of lipase from this genus and described important fermentation parameters for the enzyme production, such as nutrients, temperature, pH, inoculum, time of fermentation and others. Furthermore, different strategies have been used to purify and immobilize lipases from Geotrichum and innumerous applications are cited in different processes as polyunsaturated fatty acids enrichment, hydrolysis and esterification of fat and oils, synthesis of aromas, biodiesel, and many others. This review highlights fundamental aspects of the production, purification, characterization, immobilization, and the applications of lipases produced by the genus Geotrichum

Manejo de várzeas.

Falta p.39

Uso potencial da brita e argila na redução da toxicidade de efluentes da aquicultura contendo diflubenzuron.

Resumo: O crescimento acelerado da aquicultura no Brasil e no mundo vem a atender a uma demanda crescente por proteína animal. No entanto, este crescimento deve vir acompanhado da medidas de conservação dos recursos naturais, bem como a minimização dos impactos sobre a qualidade da água dos viveiros de criação e dos efluentes gerados por esta atividade. O presente estudo tem por objetivo avaliar a toxicidade do inseticida diflubenzuron (usado na piscicultura) sobre o organismo Artemia salina, após a filtragem com um sistema natural de tratamento de efluentes, utilizando como meios filtrantes a brita e a argila expandida. Os resultados obtidos indicam que a argila expandida foi mais eficiente na redução da toxicidade do que a brita. Embora ainda sejam necessários testes com outros organismos não alvo, sugere-se o uso da argila como filtro na saída dos viveiros para melhoria da qualidade da água do efluente

Molecular simulation of absolute hydration Gibbs energies of polar compounds

In this work, we present simulation-based predictions of the absolute hydration energy for several simple polar molecules with different functional groups, as well as for more complex multifunctional molecules. Our calculations were performed using the thermodynamic integration methodology where electrostatic and non-polar interactions were treated separately, allowing for a stable transition path between the end-points of the integration. An appropriate methodology for the analytical integration of the simulation data was applied. We compare the performance of three popular molecular mechanics force fields: TraPPE. Gromos and OPLS-AA for the description of solute atoms in MSPC/E water. It is observed that these force fields generally perform well for the simpler molecules, but are less accurate when multifunctional molecules are considered